Table 1

Reading of patch test reactions according to International Contact Dermatitis Research Group guidelines

Score
Patch test reaction
Criteria

-
Negative
No reaction
+?
Doubtful
Faint erythema only
+
Weak
Erythema, infiltration, possibly papules
++
Strong positive
Erythema, infiltration, papules, vesicles
+++
Extreme positive
Intense erythema and infiltration and coalescing vesicles

Jensen and Andersen Environmental Health: A Global Access Science Source 2003 2:3   doi:10.1186/1476-069X-2-3